Research On Risk Of Sudden Water Pollution Accidents In Ningxia Reach Of Yellow River

In recent years,the frequency of sudden water pollution accidents in river has the tendency of increasing,which posing a potential threat to water safety and water quality. The river unexpected pollution incidents occur frequently in recent years.it caused huge economic losses, but also cause serious damage to the ecological environment. Sudden water pollution accidents have become a huge threat to our national water security, aquatic ecosystems and water environment quality. It has been caused widespread concern in the community. Based on the above, taking the Yellow River in Ningxia Hui Autonomous Region as the research object, on the foundation of the determining the source of pollution, the paper apply mathematical simulation method to analyses the sudden water pollution risk.The main contents and conclusions are as follows:(1)The status of the water environment of Yellow River in Ningxia was evaluated based on the collection, collation of data and previous studies. The paper has an in-depth analysis of the reasons for the Yellow River water pollution. Considering the characteristics of the sudden water pollution accidents, the paper take the corporate irregularities or incidents sewage, transportation respectively as the sources of pollution to set simulation schemes.(2)The 1D hydrodynamic- water quality coupling model was established, based on the model calibration and validation, the paper simulated sudden water pollution accidents under different conditions. The results showed that: the impact on the outfall and the river itself more serious under dry period than that of under wet conditions. COD concentration is twice. And the arrival time is later than the wet period conditions, while the impact time on the opposite. Meanwhile the location of pollution sources is an important factor in the water intake affected by contamination, the closer the sources of pollutants to reach the shorter the time, the emergency response time is shorter, and challenges to take timely and effective measures to deal with the serious impact of sudden water pollution.(3)The 2D hydrodynamic-water quality coupling model was established to simulated sudden water pollution accidents under different conditions. Thesimulation results showed that: the impact on the outfall and the river itself more serious under dry period than that of under wet conditions. COD concentration is twice. And the arrival time is later than the wet period conditions. Compared with the 1D model, 2D model can display the pollutant distribution in the transverse direction and reflect the diffusion principle better.(4)Based on the simulation results of 1D and 2D model, the paper apply GIS technology to achieve pollution information visualization and explore the ideas and techniques to draw water pollution risk map. Pollutant concentration distribution, arrival times and pollutants affect the time distribution were drawn. But the 2D has more spatial information and easier to vectorization, it's more accurate and practical significance.The study for the sudden water pollution in Ningxia section of the Yellow River enable managers of water environment make contingency plan for the incident of sudden water pollution and provide technical support for post-incident handling. In addition, the risk map researches on river pollution can achieve pollution information visualization. What's more, they can provide the scientific technology and method for the risk analysis and assessment on river pollution events. These will promote working process in risk management of water pollution and the construction of water environment improvement and ecological civilization in our country.